Current Edition CSA A23.1: 2014
In addition to the many changes in this standard, there is a new concrete mix classification “N-CF” for “interior concrete floors with a steel trowel finish” which includes mandatory maximum 0.55 water:cement ratio and a minimum 25 MPa compressive strength (both requirements must be met see Clause 18.104.22.168.3).
Other important concrete floor items include:
- Steel fibres must be accompanied by a Certificate of Compliance and Test Reports in accordance with ASTM A820.
- Under-slab vapour retarders shall be installed in areas with non-breathing finishes and shall comply with ASTM E1745 and ASTM E1643.
- Granular bases shall be level to +/- 10mm prior to ordering a concrete placement (see Position Statement).
- The average slab on grade thickness shall be no more than 10mm less than the specified thickness and no local variations in excess of 20mm less than the specified thickness.
- Owners shall specify concrete mixes, curing and reinforcing as necessary to control drying shrinkage curling to meet their specific needs.
- Sawcut contraction joints shall be spaced at approximately 25 times the slab thickness in metres and shall not exceed 4.5m on centre.
- Semi-rigid joint fillers should not be filled earlier than 120 days after slab casting (see Position Statement).
- The Concrete Purchaser must make suitable arrangements for the plastic protection of the concrete mix being used (see Position Statement).
- Surface tolerances shall be measured within 72 hours of slab casting (See Position Statement).
- The F Number System is the only approved means of measuring floor tolerances (with an exception for small slab on grade areas up to 1500 sf see Table 21)
- Levelness tolerances do not apply to suspended slabs.
- The minimum local value (60% of overall specified value) must be exceeded in all slab areas.
- A machine trowel finish shall not be used on air entrained concrete to avoid the potential for surface delaminations.
- Concrete mixes for floors should have a MINIMUM slump of 100 mm at the point of placement.
- General use cement may be modified with up to 15% inter-ground limestone (Type “GUL” cement).
- Test method 16C permits the on-site washout of both steel and syntehtic fibres to determine the average content in concrete on site.